9514 1404 393
Answer:
(x, y) = (-1, -16) or (3, 0)
Step-by-step explanation:
Perhaps you want to solve the system of equations ...
- y = x^2 +2x -15
- y -4x = -12
Substituting the first expression for y into the second equation gives ...
x^2 +2x -15 -4x = -12
x^2 -2x -3 = 0 . . . . . . . . add 12
(x -3)(x +1) = 0 . . . . . . . factor
Solutions are the values of x that make the factors zero: x = 3, x = -1.
The corresponding values of y are ...
y = -12 +4x
y = -12 +4{-1, 3} = -12 +{-4, 12} = {-16, 0}
The solutions to the system are ...
(x, y) = (-1, -16) or (3, 0)
Answer:
20b^2
Step-by-step explanation:
Answer:
1/5
Step-by-step explanation:
Well work can be defined as: 
where rate=amount of work that can be done in one unit of time
let a = rate of work A does in a day
let b = rate of work B does in a day
this means that: 
where work=1 and it just means the entire job has been completed.
Since b can do it alone in 15 days, this means that: 
If we divide by 15 here, we get the equation: 
We can now use this definition to substitute it into the first equation we made.
Multiply the 10 and 1/15
subtract 2/3 from both sides
Now divide both sides by 10
Now multiply this by 6, since we a represents the amount of work that can be done in a day, we want to find how many parts of the work can be done by a in 6 days
Now divide both the numerator and denominator by 6
The answer is 20%
If 50 is your 100%, take 100 and 90 for example it would be obvious that is it 10% off, so with 50 since it is half of 100 you double the 10% which will be 20%. :)
plz mark me plz plz plz plz plz plz mark me
